Generally, grains such as green coffee beans, tea leaves, and the like often undergo a process of being roasted at a high temperature in a device, such as, for example, a roaster while being processed. In particular, coffee is made using roasted and ground green beans, which are seeds of certain coffee trees, and is loved by many people owing to the excellent taste and scent thereof.
Since the coffee generates a taste and scent unique to coffee when green beans are roasted at a high temperature, it is difficult to sense the desired unique taste and scent in the green beans before roasting, and thus a process of roasting the green beans is required. The taste and scent of coffee may vary considerably depending on procedures or techniques of roasting green beans as well as the difference between the kinds of coffee beans. Therefore, various devices, roasters, and the like, which are used to roast green beans so as to achieve an excellent taste and scent, have been proposed.
Accordingly, a vacuum-roasting device has conventionally been used to roast green coffee beans. The vacuum-roasting device includes a main body having a funnel-shaped introduction port in the top thereof, a rotating drum rotatably installed in the main body so that green beans are supplied into the rotating drum through the introduction port, a motor for rotating the rotating drum, and a burner for heating the lower surface of the rotating drum by supplying heat to the inside of the main body.
However, the conventional device described above is configured to heat and roast the green beans inside the rotating drum using heat supplied from the burner. At this time, the heat supplied from the burner may be concentrated on a portion of the rotating drum, more particularly, the lower surface, and moreover, the lower surface of the rotating drum may be unevenly heated to different temperatures, which may make it impossible to evenly roast the green beans inside the rotating drum, resulting in deterioration in the quality of the coffee.
In addition, as disclosed in Korean Registered Patent NO. 10-0804835, a vacuum-roasting device and a vacuum-roasting method have recently been proposed. The vacuum-roasting device includes a vacuum chamber, which includes an inlet for the introduction of an object to be processed, an opening/closing member installed thereto for opening or closing the inlet, and an outlet for the discharge of the processed object, the outlet being opened or closed by a door, a rotating drum rotatably installed inside the vacuum chamber so that the object to be processed is supplied into the rotating drum through the inlet, a rotary motor for rotating the rotating drum, a vacuum supply unit for applying vacuum pressure to the vacuum chamber, and a heater installed to the vacuum chamber.
In the above Korean Registered Patent NO. 10-0804835, after the object to be processed is supplied into the rotating drum through the inlet, the opening or closing of which is automatically adjusted, a vacuum is created inside the vacuum chamber and the object to be processed is heated while the rotating drum is rotated. With this operation and due to the advantageous configuration in which a supply port, through which the object to be processed is supplied, is installed so as to be inclined downward, the efficiencies with which the vacuum state is maintained and the outward emission of scent is prevented may be increased and the object to be processed may be evenly heated and roasted. However, the configuration described above is suitable for a large roaster, in which an object to be processed, such as, for example, coffee beans, is roasted while being continuously supplied through an inlet, and is not suitable, for example, for the case of roasting coffee beans in order to make a small amount of coffee.
For this reason, the demand for a small roaster, which may roast coffee beans to allow people to enjoy more delicious coffee even in a small shop or at home, rather than a large shop in which coffee beans need to be constantly roasted in order to make a great amount of coffee, is increasing in accordance with the increased interest in coffee and the increase in the number of small coffee shops.
In addition, since conventionally proposed devices such as large roasters for roasting, for example, coffee beans, are adapted to continuously heat coffee beans within a rotating drum, the processed object, i.e. the coffee beans, which has completely been heated, needs to be discharged outward from the vacuum chamber and then be cooled in a separate device. In this case, the processed object needs to be subjected to an additional process of removing impurities, such as, for example, husks, generated while the coffee beans are roasted within the rotating drum. Therefore, in addition to a roaster for roasting the object to be processed, for example, a separate cooling device or an impurity removal device is required, which results in an increase in the overall volume of the roaster facility once installed.